Determination of hydrogen diffusion and permeation coefficients in pure copper at near room temperature by means of tritium tracer techniques

Copper (Cu) and its alloys are candidate materials for heat sinks or cooling-tubes in a fusion reactor. Hence their tritium retention and permeation are very important safety concerns. Most data for diffusion and permeation of hydrogen in Cu so far available have been limited for rather higher temperatures and data for lower temperatures, in particular, for near room temperature (RT) are scarce. We have applied a tritium tracer technique for gaseous hydrogen permeation in pure Cu at near RT and succeeded to get reliable data for hydrogen permeation coefficients given by Phi = (2.8 +/- 0.4) x 10(-6) exp(-85 +/- 2(kJ/mol)/RT), mol m(-1) s(-1) Pa-1/2, which is reliable in very wide temperature range from 300 K to 1000 K. However, diffusion coefficients determined by the time-lag method are bending downward from the extrapolation of higher temperature data and are influenced by initial surface contamination which is removed by hydrogen loading. (C) 2013 Elsevier B.V. All rights reserved.